Process for forging cylinder heads



Dec. 11, 1945.

, C. A. BRAUCHLER PROCESS FOR FORGING JYLINDER HEADS Filed March 31. 1943 7 Sheets-Sheet 1 0/24/ 265 AB/wm aunt/114430 Dec.11, 1945 .A.'BRAU CHL'ER 23905867 PROCESS FOR FORGING CYLINDER HEADS Filed Ma t-c1131, 1943 7 Sheets-Shed 2 a. E6 K 3P I l I I Dec. 11, 1945. c. A. BRAUCHLER PROCESS FOR FORGING CYLINDER HEADS Filed March 51, 1945 'T'Sheets-Sheet 5 maria; flfirma'hler 3% 7W fv g I Dec. 11, 1945. c. A. BRAUCHLER 2,390,867

PROCESS FOR FORGING CYLINDER HEADS Filed March 31, 1943 '7 Sheets-Sheet 4 /zal'la flBrczac/zler Dec. 11, 1945. c A. BRAUCHLER 2,390,867

PROCESS FOR FORGING .CYLINDER' HEADS Filed March a1, 1943 "r Sheets-Sheet 6 Dec. 11, 1945. c. A. BRAUCHLER PROCESS FOR FORGING CYLINDER HEADS Filed March 31, 1943 7 Sheets-Sheet 7 /zarlesfirauwer Patented Dec. l1, Y

UNrreos'rATEs PATENT OFFICE 2,390,867 rnoosss Foa FORGING cYLmnEa am s Charles Brauchl'er, CantomOhio Application March 31, 1943, Serial No. 481,193

13 Claims. (01. 29-15e.4)'

The invention'relates to the forging of cylinder heads and other parts from aluminum alloys and similar metals, and more particularly to a novel forging process in which the forgings are pressed rather than the usual practice of hammering.

The process is particularly concerned with the production of cylinder heads ,foraircraft engines, and to this end the present application illustrates and describes the invention as applied to the manufacture of 'cylinderheads for aircraft engines.

' permitting these chambers to be enlarged, resulting in increased power output and decreased fuel consumption, thus extending the range of operations of planes, so important in present daywarfare.

However, a serious obstacle in the way of manufacturing these forged heads is the limited number of drop hammers in the country with Under present practice. these cylinder'heads are cast from aluminum or aluminum alloys, such 1 On the other hand, if a heavier casting were to be adopted, increased cooling area would necessarily have to be provided to dissipate the heat. and this in turn would necessitate a larger head requiring more space, and thus the vicious circle would continue, resulting in increasing the overall dimensions of the engine and adding to the weight of the airplane, thus reducingboth its speed and load carrying capacity.

For this reason aircraft engineers, reluctant to increase the weight of the engines by making a more massive cylinder head, have been recently engaged in development work to produce a forging to replace the conventional, cast cylinder head, because if a forging could be employed the increased tensile strength of the forged material overthat of cast material would result ina cylinder head of twice the strength without any increase in weight or size while the greater thermal conductivity would considerably increase the I cooling effect, and as the temperature of the cylinder head has a direct bearingon the power produced, this increased cooling of the head is of considerable importance.

. A forged cylinder head would thus give planes a decided advantage in desert or tropical fighting and also permit .the development of increased power at hmh altitudes. strength of the forging makes possible thinner walls around the intake and exhaust chambers,

Further, the greater suilicient power to produce these heads, and the heavy demands upon drop hammers for many other forged articles for war use. Since a. minimum of nine hammer forging operations is required to produce'one cylinder head forging and because it was found upon investigation that suilicient drop hammers to produce these forgings in any considerable numbers could not be obtained for about two years, it has been impossible up to the present time to equip airplane engines with forged cylinder heads.

Applicant however has overcome these obstacles and has developed the process embodied in the present invention, by which the forged cylinder heads are formed in a mechanical or hydraulic press in two operations, thus obtaining all of the advantages of the forged cylinder head without the use of drop hammers and with only a fraction of the labor and time required for drop forging the head; thereby freeing much needed drop hammers, as well as foundry equipment for other essential work.

It is therefore an object of the invention to provide a process for quickly and economically producing forgings for cylinder heads and the like by heating the metal to forging temperature and squeezing or pressing it in a mechanical or hy- :process for forging cylinder heads, and the like,

through two dies. the first die forming the rocker boxes and the second forming the outside contour of the head. The combustion recess may be formed by machining or may be formed in athird die, in an upsetting operation in which operation a skirt may be extruded around the combustion recess where desirable.

The second and third steps may be combined in one operawith-a minimum of flash, thus preserving the original flow lines of the metal grain and producing a, stronger finished product than that obtained by drop hammer forging where the flow lines curve outward towards the flash and are intersected during the machining operation.

-'1"he above objects and advantages, together accuser The first operation of the process is carried out w in the lower and upper dies, shown at is and 2B with others which will be apparent from the drawings and following description, or which will be later referred to, may be attained by carrying out the improved forging process in the manner hereinafter described in detail and illustrated in the accompanying drawings, in which- Figure 1 is a perspective view of an extruded or rolled bar stock blank approximating the general shape of the cylinder head;

Fig. 2, a perspective view of the partly com pleted product after the first forging operation;

. .tively, to form the rocker boxes upon the head,

and the lower die may be provided with the bosses 23 for forming the intake and exhaust recesses in Fig. 3, a perspective view of the forged cylinder head after the second forging operation;

' Fig. 4, an elevation partly in section of the forged cylinder head after the combustion recess has been formed therein and the skirt extruded as by a third operation upon an upsetting machine or the like; V

Fig. 5, a bottom plan view of the forged cylinde'r head shown in Fig. 4;

Fig. 6, a perspective view of the finished forged head after the same has been machined;

Fig. 7, a vertical sectional view of the forging dies used in the first operation showing the dies in open position with a blank positioned therein ready for the first forging operation;

Figure 8 is a side elevation of the partly completed product produced in the dies shown in -F18.7;

the head.

The blank, which may beof any of the shapes above referred to, is heated to forging temperature and'placed in the lower die l9 as shown in Fig. 7 and the press is then operated-to move the upper die 20 down upon the lower 'die'. As the press may be of substantially 2500 tons capacity the heated blank will be squeezed under this extreme pressure to the contour of the dies producing the partially completed forged product indicated generally at 24 in'Figs. 2,8, 9 and 12.

In this first pressing operation the surface of the blank between the angular ribs II. and i8 is partially rounded as indicated. at 24a in Fig. 2,

said ribs l1 and It! being tapered toward each end and rounded at one end, the blank being recessed at the opposite end of the rib il as indicated at Nb and partially rounded at the corresponding end of the other rib as indicated atoppositely tapered portion 21. upon one sidefgiof the partially completedproduct, just below-the partially formed rocker box 28. this enlarged Fig. 12, a vertical sectional view through the partly completed forged product of the first operation showing the grain flow;

Fig. 13, a similar view of the forged 'head'as produced by the second operation, showing the grain flow; and v Fig. 14, a sectional view showing .jplunger for the upsetting operation.

Similar numerals refer to similar parts throughout the drawings.

the dies and j In carrying out the improved forging rocess .the cylinder head is forged from a blank of suit- "able size composed of an aluminum alloy which :,-'may be modified duralumin comprising substantially 90% aluminum and the balance made up of small amounts of several different metals.

This blank may be the usual substantially indicated generally at I l and as shown in detail in Figure 1, comprising the substantially recportion being for the purpose of cutting cooling-- fins in the'cylinder head adjacentto the exhaust rocker box 26, and may also include .the partial formation of inlet and exhaust ports in underside of the forging.

- If the partially completed forged produ retains suflicient heat for further'forgiiig it be immediately placed in the dies for operation shown in Fig. 9 and indicated-remistively as the lower and upperv dies 1|,

necessary the partially completed forgini be reheated to forgin temperature before it placed in the dies for the second operation;

These dies are shapedss'indicated atjl-and ila. respectively to produce the outside V of the head when the press is operated to. b11118 the dies together. squeezing the "hot forging-F24 to the finished shape indicated gener n E -B, i0 and 13. .1

"In this operation the top of the head is generally rounded as indicated at If. the lower p rtion of the head is formed to generally circular shapeas indicated at 38: the intake and exhaust recesses 28 are formed deeper into themed. and

"the same is'recessed as at ll. adiacent to these tangular body portion It and the oppositely dis- I posed angular ribs l1 and I8 at two adjacent corners of the block for producing the rocker boxes at the inlet and exhaust sides of the cylinder head.

side of the head is rounded; and the rocker boxes II and 28 are shortened andreduced to substantially the finished outside contour as indicated at fla-and 26a respectively, the ends thereof bein further tapered and, if desired, bosses are formed thereon to form bearings for rocker shafts and the "like.

The combustion recess ll may be formed in the lower side of the head by machining. or if and the upper I emergency,

upsetting operation.

This upsetting operation may be carried out in apparatus such as shown. in prises generally a stationary lower die ed upon a bed 45, a vertically movable upper die 46 operated by a piston 41 of a hydraulic cylinder, or the like, and a plunger 48 operated by a piston 49 of a hydraulic cylinder, or the like.

The forging, as shownin Figs. 3 and 10, at forging temperature, is inserted through the opening 50 in the end plate 5|, and placed in the lower die 44. The upper die 46 is then moved downward to the position shown in Fig. 14, holding the hot forging between the dies and the plunger 48 is moved inward, or toward the left as viewed in said figure forming the combustion recess 35 and extruding the skirt 36 around the same. i

It has been found that, if desired, the production of these forgings may be further shortened by eliminating the step in which the forging shown in Figs. 3 and is produced. For this purpose the partially completed product shown in Figs. '2 and 9, at forging temperature, may be placed in the lower die 44,

die 46 is forced down, ing the outer contour shown in said figure.

The plunger 48. is then operated to form the combustion recess 85 inthe forging'and at the same time extrude the skirt 36, while the hot forging is held between the dies 44 and A6.

The finished forging as shown-in Fig. 4, with the combustion recess and skirt formed thereon,

44 mountpress forgofthe product to the shape may thus be produced in two, and a maximum' of three operations, ready for machining to produce the finished cylinder head, as compared with a minimum of nine hammer forging operations to produce the same forging.

' And it will be evident that the forging is completed without the use of drop hammers, of which there is an acute shortage during the present freeing the hammers for the production of othernecessary products.

Cylinderheads forged by the improved process have a finer and more uniform grain structure in the metal than the conventional cast heads and have a more uniform. grain flow pattern than hammer forged heads. This is due to the fact that excess metal is not squeezed out in a substantialflash as in drop hammer forging thus eliminating the ouwardly curved flow lines which are intersected during the machining operation.

As shown in Figs. 11, 12 and 13 the flow line pattern of the head forged by this process is unbroken and substantially follows the outer contour of the forging, eliminating the usual outward curve toward the flash, which is intersected by machining resulting, in weakening of the forged article- As shown in Fig. 11 the grain flow, indicated at 31, is in a-longitudinal direction and straight throughout the area of the blank. After the first forging operation, as shown in Fig. 12, it will be seen that the grain flow near the outside of the forging substantially follows the contour of the forging and is unbroken at the meeting surfaces of the dies where the relatively slight flash I8 is formed, this grain flow being indicated at 81a in Figure 12.

After the second forging operation,.as shown in Fig. 13, the grain flow indicated at 31b is-still Fig. 14, which comshown in Fig. 14,

ished cylinder head. I

Thefinished forging may then be machined as shown in Fig. 6 cutting cooling fins, as indicated at 40, circumferentially'around the lower portion 33 of the head and cutting cooling fins as indicated at 4| over the rounded upper portion 32 of the head between the rocker boxes 25a and 26a and cutting additional cooling fins 42 around the enlarged portion 2111 on the exhaust side thereof.

The increased tensile strength over the cast head, without increase in weight or size, and the greater thermal conductivity of the forged metal substantially increases the cooling effect as much Furthermore, the increased strength of the forging achieved by the finer, more uniform and substantially unbroken grain structure in the metal makes possible thinner walls around the intake and exhaust chambers of the head, thus permitting these chambers to be enlarged producing an increase in power output and a. decrease in fuel consumption, thus increasing the range, speed and load carrying capacity of planes equipped with these engines and at the same time substantially reducing the weight of the engine.

It has been found in actual practice that the horse power output of engines provided with these forged cylinder heads is increased as much as 15% while the weight is reduced as much as three and one-half pounds per cylinder, and in planes powered by four eighteen-cylinder motors it will be seen that this is a substantial reduction in weight.

Under present practice approximately 20% of the cast cylinder heads are rejected while it has been found that at least 95% of the forged heads pass the final inspection as finished parts of the labor and material.

so as to form the entire finished I claim:

1. The method of producing a forged engine cylinder head having thick walls for the formation of deep cooling fins, which consists in making the cylinder head solely by press forging and which comprises the steps of forming a substantially rectangular aluminum alloy blank having angular ribs at two adjacent corners thereof, heating said blank to forging temperature, forging the hot metal in one pressing operation said pressing operation including partially rounding the surface of the blank between said angular ribs, tapering the ribs toward each end, rounding one end of each rib, recessing the blank at the other end of one rib and partially rounding the blank at the corresponding end of the other rib so as to said second pressing operation including further rounding the upper portion of the head between the rocker boxes, substantially circularizing the lower portion of the head, shortening the rocker boxes and further tapering them at each end outside contour of thehead and the contour of the outer edges of the cooling fins entirely by forging.

2. The method of producing a forged engine cylinder head having thick walls for the formation of deep cooling ing the cylinder head solely by.

' unbroken and follows the outside contour of theforging. This highly desirable flow grain .pattern adds substantially to the strength of-the finpartially form said angular ribs into rocker boxes and then forging the hot, parfins, which consists in makpress forging amiwhich comprises the steps of forming a substantially rectangular aluminum alloy blank having angular ribs at two adjacent corners thereof, heating said blank to forging temperature, forging the hot metal in one pressing operation said pressing operation including partially rounding the surface of the blank between said angular ribs, tapering the ribs toward each end, rounding one end of each rib, recessing the blank at the other end of one rib and partially rounding the blank at the corresponding end of the other rib so'as to partially form said angular ribs into rocker boxes and to partially form the outside contour of the head and then forging the hot, partially forged product exactly as produced by said first operation in a second pressing operation said second pressing operation including further rounding the upperportion of the head between the rocker boxes, substantially circularizing the lower portion of the head,= shortening the rocker boxes and further tapering them at each end so as to form the entire finished outside contour of the headand the contour of the outer edges of the cooling fins entirelyby forging.

3. The method of producing a forged engine cylinder head having thick walls for the formation of deep cooling fins, which consists in mak .ing the cylinder head solely by press forging and which comprises th steps of forming a substantially rectangular having angular ribs at two opposite corners thereof, heating said blank to forging temperature, forging the hot metal in onepressing operation said pressing operation lncliiding. .partially rounding the surface of the blank between said angular ribs, tapering the ribs toward each end, rounding one end of each rib, recessing the blank at the other end of one rib and partially rounding the blank at the corresponding end of the other rib? so as to partially form said miller ribs into rocker boxes and to partially form intake and exhaust recesses in the blank and then forging the hot, partially forged prodnot exactly as produced by said first operation.

in a second pressing operation said second pressing operation including further rounding the bugl er porti on of the head between the rocker X tion of the head, shortening the rocker boxes and further tapering them at each end so as to form the entire finished outside contour of thehead and the contour of the outer edges of the cooling fins entirely by forging and to deepen .the intake and exhaust recesses. 4

producing a forged engine I 4. The method of' cylinder head having tion of deep cooling ing the cylinder head solely by press forging and which comprises the steps of forming a substanthick wallsfor the forma- .tially rectangular aluminum alloy blankhaving angular ribs at two opposite corners thereof, heating said blank to forging temperature, forging the hot metal'in one pressing operation said pressing operation including partially rounding the surface ofthe blank between said angular ribs, tapering the ribs toward each end, rounding one'end ofeach rib, recessing. the blank at the other end of one rib and partially. rounding the blank at the corresponding end of the other rib so as to partially fomi said-angular ribs into rocker boxes and to partially form the outside contouroftheheadandtopartiallyformintake and exhaust in the blankand then forging the hot, i forged product exabtly aluminum alloy blank assess? w as produced by said first operation in a second pressing operation said second pressing operation including further rounding the upper portion of the head between the rocker boxes, substantially circularizing the lower portion of the head, shortening the rocker boxes and further tapering them at each end so as to form the entire finished outside contour of the head and the contour of the outer edges of the cooling fins entirely byforging and to deepen the intake and exhaust recesses.

5. The-method of producing a forged engine cylinder head having thick walls for the formation of deep cooling fins which consists in making the cylinder head solely by press forging and and then forging the hot, partially forged prod-' not exactly as produced by saidfirst pressing operation in a second pressing operation, said second pressing operation including further rounding the upper portion of the head between. the

er portion of the head, shortening the rocker boxes and further tapering them at each end so as to form the entire finished outside contour a pressing operation substantially circularizing the lower porfins, which consists in make portion of of the cylinder head and rocker boxes thereon;

6; The method ofproducing a forged engine cylinder head having thick walls for the formation of.deep cooling fins which consists in making the cylinder head solely by press forging and which comprises the steps of heating an aluminum alloy blank to ing the hot metal in one pressingoperation, said including partially forming rocker boxes upon two adjacent corners of the blank, tapering said partially formed rocker boxes toward each end, rounding one end of each partially formed rocker box, recessing the blank at the other end of one partially formed rocker box and partially rounding the blank at the corresponding end of the other partially formed rocker box, forming an enlarged, oppositely tapered portion upon one side of the blank just below'one of the partially formed rocker boxes and rounding the surface of the blank between said partially formed rocker boxes, and then forging the hot, partially forged product exactly as produced by said first pressing operationin a second pressingroperation. said second pressing operation including further rounding the upper the head between the rocker boxes, substantially circularizing the lower portion of the head, shortening the rocker boxes and further tapering them at each end so as to form the entire finished outside contour-of the cylinder head sndrccker boxes thereon; 'I. The method of producing a forged engine cylinder head having thick walls for the formation of deep cooling fins which consists in making the cylinder head solely by press forging and which comprises the steps of beating an alumighun alloy blank to forging temperature, to

hot

forging temperature, ms

metal in one pressing operation, at

pressing operation including partially forming rocker boxes upon two adjacent corners of the blank, tapering said partially formed rocker boxes toward each ,end, rounding one end of each partially formed rocker box, recessing the blank at the other end of one partially formed rocker box and partially rounding the blank atthe corresponding end of the other partially formed, rocker box, partially forming inlet and exhaust ening the inlet and exhaust ports, shortening the rocker boxes and further tapering them at each end so as toform the entire finished outside contour of the cylinder head and rocker boxes thereon,

8. The method of producing a forged engine cylinder head having thick walls for the formation of deep cooling fins which consists in making the cylinder 'head solely by press forging and which comprises the steps of heating an aluminum alloy blank to forging temperature, forging the hot metal in one pressing operation, said pressing operation including partially forming rocker boxes upon two adjacent corners of the blank, tapering said partially formed rocker boxes toward each end, rounding one end of'each partially formed rocker box, recessing the blank at the other end of one partially formed rocker box and partially rounding the blank at the corresponding end of the other partially formed rocker box, forming an enlarged, oppositely tapered portion upon one side of the blank Just below one of the partially formed rocker-boxes and rounding the surface of the blank between said partially formed rocker boxes, and then forging the hot, partially forged product exactly as produced by said first pressing operation in a second pressing operation, said second pressing operation including further rounding the upper portion of the head between the rocker boxes, substantially circularizing the lower portion of the head, rounding the enlarged, oppositely tapered portion, shortening the rocker boxes and further tapering them at each end so as to form the entire finished outside contour of the cylinder head and rocker boxes between-the rockerlboxes, substantially circu-' larizi-ng the lower portion of' the-head, rounding -.the enlarged, oppositely taperedportion, deepening the inletand exhaust ports, shortening the rocker boxes and further tapering them at each end so as to form' the entire finished outside contour of the cylinder head and thereon,

rocker boxes 10. The method of producing a forged engine cylinder'head having thick walls for the formation of deep cooling fins which consists in making the cylinder head solely by press forging and which comprises the steps of heating an aluminum alloy blank to forging temperature, forging the hot metal in one pressing operation,'said pressing operation including partially forming rocker boxes upon two adjacent comers of the blank, tapering said partially formed rocker boxes toward each end, rounding one end of each partially formed rocker box, recessing the blank at'the other end of one partially 'formedrocker box and partially rounding the blank at the corresponding end of the other partially formed rocker box and rounding the surface of the blank between said partially formed rocker boxes, and

' then forging th hot, partially forged product exactly as produced by said first pressing operation in a second pressing operation, said second pressing operation including further rounding the upper portion of the head between the rocker boxes, substantially circularizingthe lower portion'of the head, shortening the rocker boxes the blank at the corresponding end of the other ing the cylinder head solely by press forging and blank, tapering said partially formed rocker boxes toward each nd, rounding one end of each partially formed rocker box, recessing the blank at the other end of one partially formedrocker 'box and partially rounding the blank atthe corresponding end of the other partially formed rocker box, forming an enlarged, oppositely tapered portion upon one side of the blank just and further tapering them at each end and forming bosses upon-the rocker boxes so as to form the entire finished outside contour of the 7 cylinder head and rocker boxes thereon.

, 11. The method of producing a forged engine cylinder head having thick walls for the formation'of deep cooling fins which consists in making the cylinder head solely by press forging and which comprises the steps of heating an aluminum alloy blank having a longitudinal grain structure to forging temperature, forging the hot metal in one pressing operation, said pressing "operation including partially forming longitudinally disposed rocker boxes upon two adjacent corners of the blank, tapering said partially formed rocker boxes toward each end, roundin one end of each partially formed rocker box, reoessing th blank at the other end of one partially formed rocker box and partially roundin partially formed rocker box and rounding the surface of the blank between said partially formed rocker boxes, and then forging the hot,

partially forged product exactly as produced by said first pressing operation in a second pressbelow one of the partially formed rocker boxes,

partially forming inlet and exhaust ports in the underside of the blank, and rounding the suring operation, said second pressing operation including further rounding the upper portion of the head between the rocker boxes, substantially circularlzing the lower portion of the head.

shortening the rocker-boxes and further tapering them at-each end so as to form the entire finished outside contour of the cylinder head and rocker boxes thereon with substantially no flash whereby the flow line pattern of the grain of the metal is caused to conform to the contour of the head.

12. The method of producing a forgedengine face of the blank between said partially formedcylinder head having thick walls for the formation of deep cooling fins which consists in making the cylinder head solely by press forging and which comprises the steps of heating an aluminum alloy blank having a longitudinal grain partially formed rocker box and rounding the surface of the blank between said partially formed rockerboxes, and then forging the hot,

partially forged product exactly as produced by said first pressing operation in a second pressing operation, said second pressing operation including further rounding the'u'pper portion of the head between the rocker boxes, substantially circulari zing the lower portion shortening th rocker boxes and further tapering them at each end so as to form the entire finished outside contour of the cylinder head and rocker boxes thereon and then forming a combustion chamber recess in the forged head by an upsetting operation with substantially no flash whereby the flew line pattern of the grain of the metal is caused to conform to contourof the head.

tion of deep cooling fins which consists in making the cylinder head-solely by press forging and which comprises the steps of heating an aluminum alloy blank having a longitudinal grain structure to forging temperature, forging the hot metal in one pressing operation, said pressing operation including partially forming longitudinally disposed rocker boxes upon two adjacent corners of the blank, tapering said partially 18. The method of producing a forged engine cylinder head having thick walls for the forma-= formed rocker boxes toward each end, rounding one end of each partially formed rocker box, recessing the blank at the other end of one partially formed rocker box and partially roundin the blank at the corresponding end of the other partially formed rocker box and rounding the surface of the blankv between said partially formed rocker boxes, and then forging the hot. partially forged product exactly as produced by said first pressing operation in a second pressing operation, said second pressing operation including further rounding the upper portion of the head between the rocker boxes, substantially circularizing the lower portion, shortening the rocker'bcxes and further-tapering them at each end so as .to form the entire finished outside contour ofthe cylinder head and. rocker boxes thereon and then forming a combustion'chamber recess in the forged head and simultaneously extruding a skirt around it by an upsetting operation with substantially no flash whereby the flow line pattern of the grain of the metal is caused to conform to the contour ofv the head. 

